This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Both warfarin and aspirin are effective in reducing rates of stroke and death in many patient populations, but they also carry risks of hemorrahage. They have not been directly compared in patients with heart failure and thus, it is not clear which is better for this patient group. WARCEF is a randomized, double-blind, multicenter clinical trial to compare warfarin and aspirin in patients with heart failure. The primary specific aims is to determine whether warfarin or aspirin is better for preventing all-cause mortality and stroke combined in patients with ejection fraction (EF) 30%, when balanced against any risk of interacereral hemorrhage. The primary endpoint is cited with the occurrence of death from any cause, ischmic stroke, or intracerebral hemorrhage (ICH). The warfarin dose will be adjusted to achieve an International Normalized Ratio (INR) between 2.5-3.0, with a target INR of 2.75. The aspirin dose is 325 mg/day. WARCEF also has several secondary goals, including analyzing subgroups (women, African Americans, ejection fraction groups, heart failure class) and examining the effect on cognitive function. For descriptions of the primary and secondary aims, refer to the WARCEF Protocol, version 2.0. The primary Specific Aim of this randomized, double-blind, multi-center clinical trial is to determine whether warfarin (International Normalized Ratio (INR) 2.5-3.0, target INR 2.75) or aspirin (325 mg per day) is better for preventing all-cause mortality and stroke combined in patients with ejection (EF) 20%. The primary null hypothesis is that, with patients with EF or = to 35%, there is no difference between warfarin (INR 2.5-3.0 with a target INR of 2.75) and aspirin (325 mg per day) therapies relevant to time of occurrence death from any cause, ischemic stroke, or intracerebral hemorrhage (ICH). This is tested against the alternative hypothesis of a non-zero difference between these two treatments, at @=.05 two sided, with power of 89% to detect a 17.82% hazard rate reduction (after appropriate allowance for crossover and loss to follow-up), with symmetrical stopping and decision rules.